sink into something
phrasal verb with sink verb uk/sɪŋk/ us/sɪŋk/ sank or sunk | sunk
（放松地）坐下，躺下
to slowly move your body into a sitting or lying position, in a relaxed or tired way
I was so tired when I got home that all I wanted to do was sink into bed/an armchair/a hot bath. 我回家后太累了，只想躺在床上／坐到扶手椅里／洗个热水澡。